burning glass

noun

1. a converging lens used to produce heat or ignite substances by focusing the sun's rays.

burning glass

noun

1. a convex lens for concentrating the sun's rays into a small area to produce heat or fire

Word History and Origins

Origin of burning glass¹

First recorded in 1560–70

Example Sentences

I took the precaution, however, to put the burning-glass into my pocket lest we should want fire.

From Project Gutenberg

They lack the burning glass of a purpose, to focalize upon one  spot the separate rays of their ability.

From Project Gutenberg

He was like a great burning glass, concentrating the rays of the sun upon a single spot; he burned a hole wherever he went.

From Project Gutenberg

To show the action of a burning glass send a beam of light into a darkened room, and place in its path a double convex lens.

From Project Gutenberg

That burning glass is what did it, said one more reflective man.

From Project Gutenberg